Vine mealybug and nematodes, though small, can cause major damage to the roots of wine grapes, drastically reducing yield and vine health. But growers who invest in proactive measures can safeguard the longevity of these high-value crops.
Tiny Bugs, Big Problems
Year-round, vine mealybug infestations can wreak havoc on all parts of the plant, including the roots. These tiny pests produce a substance called “honeydew” that resembles candle wax if found in large amounts and leads to the growth of black sooty mold on wine grape crops.
According to researchers at Oregon State University, vine mealybug and similar pests carry grapevine leafroll associated viruses. Not only can these diseases reduce yield by up to 40 percent, they also cause leaf discoloration, lower fruit quality and can affect production in future seasons.
Root-knot nematodes are another ubiquitous pest found in California vineyards. These tiny roundworms puncture plant roots, causing the formation of root galls. The knots make it more difficult for the plant to take in vital nutrients, which leads to reduced yield and vine vigor. Like the vine mealybug, root-knot nematodes can also be found year-round, never allowing growers a moment of rest.
A Multilayered Solution
Controlling vine mealybug and nematode populations is essential to protecting overall vine health. Vigilant monitoring and cultural practices paired with crop protection products can limit the impact of these damaging insects.
Monitoring for vine mealybugs starting at bloom is essential for season-long suppression. Researchers at the University of California recommend placing two pheromone traps for every 20-40 planted acres in late spring and checking them every two weeks through November. Growers are also encouraged to clean plant parts from equipment when moving from an infested area of a vineyard to an unaffected one.
Movento® insecticide provides long-lasting protection, posing low risk to natural predators, and works well in integrated pest management programs. Trials conducted by the University of California Cooperative Extension, Kern County, indicated that an early-May application of Movento led to a 94 percent decrease in the number of vine mealybugs found on grape vines.
A separate three-year trial found that Movento, combined with Admire® Pro insecticide, significantly reduced root-knot nematode populations over time compared to untreated vines. A post-harvest application of Movento provides residual protection to positively impact yield for the next season and beyond.